The suspect in a shooting at a leading French newspaper office had lived in Britain for several years before returning to France in July, according to the Associated Press.
Abdelhakim Dekhar remains in custody in a suburban Paris hospital after police detained him on Wednesday night, the Paris prosecutor said.
Prosecutor Francois Molins told reporters that the witness who turned Dekhar in said he had been staying with him and that they had met while working in a restaurant together in London 13 years ago.
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Despite the use of combustible cladding in tower blocks, ministers were advised that regulations were tough enough, ITV News has learnt.
A milder night across the north than last night, with rain sneaking into southern Scotland from Northern Ireland.
The singer, 31, said on Twitter that she and her partner Jonathan Powell were grieving their loss.